Gross domestic product, the value of all goods and services produced, rose at a 3.9 percent annualized rate, up from an initial estimate of 3.5 percent, Commerce Department figures showed today in Washington. The median forecast of 81 economists surveyed by Bloomberg called for a 3.3 percent gain. After the 4.6 percent increase in the second quarter, it marked the biggest back-to-back advance since late 2003.

Companies such as Wal-Mart Stores Inc. are seeing the benefits of the steadily improving economy as a strengthening labor market and gains in sentiment underpin consumer spending. The outlook for growth supports the Fed's recent decision to complete its bond-buying program, and central bankers continue to monitor economic progress while deciding when to raise interest rates for the first time in the recovery.

"We probably have more momentum heading into the final quarter of the year," said Brian Jones, a senior U.S. economist at Societe Generale in New York, whose estimate of 3.8 percent growth was closest in the Bloomberg survey. "We're probably on pace for another 3 percent to 3.5 percent growth in the final three months."